Emergency Floatation Systems in Helicopters

Emergency floatation systems (EFS) are designed to prevent a helicopter from sinking or capsizing after making a controlled ditching or water impact. Such accidents are rare, but an EFS can buy time for emergency rescue services to arrive and save the occupants.

The fitting of an EFS based on floats is well established, but the issue of instability on anything other than a calm surface of water has always been problematic. This is because helicopters have a high sense of gravity due to the location of the rotors, transmission, and engines at the top of the helicopter’s fuselage, which makes tipping over easy. The floats that provide EFS buoyancy are packed within spaces inside the airframe or fitted as externally mounted packs on the lower structure. Inflation is provided by gases stored in pressurized cylinders carried onboard. Helium is the primary gas used in these cylinders due to its ability to rapidly inflate the floats, but others are mixed in as well.

Helicopters with EFS must be certified that it functions properly, but there are still hazards. Emergency floatation systems can be damaged by the impact, and harsh sea conditions can also cause safety issues. Therefore, the UK Civil Aviation Authority recommended in 2014 that “in order to minimize the probability of post ditching capsize, operations should be prohibited when the sea conditions at the offshore location that the helicopter is operating to/from exceed its certified ditching performance.” Ways of improving the crashworthiness of float systems have also been considered, and it is considered by many that the EFS should be manually armed for all overwater arrivals and departures, and where practicable activated automatically in all water impacts when not armed. An Automatic Float Deployment System adds additional functionality to an EFS and was the subject of one of the twenty-seven safety recommendations made by the UK Air Accidents Investigation Branch.

Another recommendation for increasing crashworthiness is installing additional floats to ensure that even if a helicopter does not remain upright, whether due to float damage during the crash or sea conditions, it will list to one side rather than completely capsize and sink. The European Safety Agency has investigated this option and found that adding EBS floats at the tops of the cabin walls made it possible to leave a helicopter listing on its side even in rough sea conditions.